Swap every spoonful of added sugar for stevia and the climate bill doesn't move. The water bill goes up 11%

Most research on sweeteners asks what they do to our bodies. A team from the University of Surrey, the Dutch food-data firm Blonk and partners in the EU-funded SWEET project asked a different question: if a whole diet swapped its added sugar for a low-calorie sweetener, what would happen to the planet? Their answer appeared in the European Journal of Nutrition on 7 October 2026, and it is the first attempt to do the sum across an entire diet rather than for one drink or one yogurt.

They started from the Dutch national food survey of 2019 to 2021 and picked the 143 adults aged 18 to 50 (72 men, 71 women) who ate more than 2,200 kcal a day, an average of 2,866. Using recipe data they estimated 54 grams of added sugar a day, 8% of calories, which the authors themselves think is on the low side. Then every gram was replaced on paper with a stevia extract plus whatever had to fill the space sugar left behind: sorbitol in cakes, biscuits and sweets, plain water in soft drinks, a maltitol syrup where glucose syrup had been, milk in dairy desserts, and stevia alone in the sugar people stir into tea. Each food was then linked to life-cycle data covering farming, processing, transport, packaging, cooking and waste.

The carbon footprint of the sweetener diet was 4.18 kg of CO2-equivalent a day, exactly the same as the sugar diet. Underneath, things moved in opposite directions. Soft drinks got about 16 grams of CO2 a day cleaner, because stevia and water have a smaller footprint than beet sugar. Cakes and sweet biscuits went up by 6.6 grams and sugar and confectionery by 5.1, because sorbitol is made by further processing glucose from wheat starch and costs more to produce than the sugar it replaces. Land use barely changed and nutrient run-off into the sea fell 3%, but water use rose 11%, from about 119 to 133 litres a day per person. Calories fell 5%, from 2,866 to 2,728 a day, and total sugars dropped from 125 to 71 grams.

The team then let a computer adjust both diets as little as possible to meet Dutch nutrient targets, and again to also hit a 2030 food emissions target of 2.04 kg CO2 a day, roughly half of today's figure. Both diets needed almost the same amount of change to get there, mostly fewer sweet snacks, more legumes and nuts and, for the climate goal, less meat. Water use rose when legumes doubled and fell 11 to 15% once meat came down. The authors' reading is that sweeteners neither help nor hurt the climate much, so the case for cutting sugar can rest on health. They are open about the limits: replacing every gram of sugar is a thought experiment, only 42% of foods matched the life-cycle database directly, all sugar was assumed to be beet (cane, about 80% of world supply, has a bigger footprint on most measures), and real products are usually reformulated more cleverly than with one bulking agent. Some authors have industry ties: one works for the ingredients company Cargill, and others declared honoraria or project funds from sweetener and beverage associations.